The following discussion is intended to facilitate the understanding of the invention, but is not intended nor admitted to be prior art to the invention.
A. Osteoporosis
Osteoporosis is a disabling disease characterized by the loss of bone mass and microarchitectural deterioration of skeletal structure leading to compromised bone strength, which predisposes a patient to increased risk of fragility fractures. Osteoporosis affects more than 75 million people in Europe, Japan and the United States, and causes more than 2.3 million fractures in Europe and the United States alone. In the United States, osteoporosis affects at least 25% of all post-menopausal white women, and the proportion rises to 70% in women older than 80 years. One in three women older than 50 years will have an osteoporotic fracture that causes a considerable social and financial burden on society. The disease is not limited to women; older men also can be affected. By 2050, the worldwide incidence of hip fracture in men is projected to increase by 310% and 240% in women. The combined lifetime risk for hip, forearm, and vertebral fractures presenting clinically is around 40%, equivalent to the risk for cardiovascular disease. Osteoporotic fractures therefore cause substantial mortaility, morbidity, and economic cost. With an ageing population, the number of osteoporotic fractures and their costs will at least double in the next 50 years unless effective preventive strategies are developed. (See, e.g., Atik et al., Clin Orthop Relat Res (2006) 443:19-24; Raisz, J Clin Invest (2005) 115:3318-3325; and World Health Organization Technical Report Series 921 (2003), Prevention and Management of Osteoporosis.)
B. Obesity and Diabetes
Obesity is a major public health concern because of its increasing prevalence and associated health risks. Moreover, obesity may affect a person's quality of life through limited mobility and decreased physical endurance as well as through social, academic and job discrimination.
Obesity and being overweight are generally defined by body mass index (BMI), which is correlated with total body fat and serves as a measure of the risk of certain diseases. BMI is calculated by weight in kilograms divided by height in meters squared (kg/m2). Overweight is typically defined as a BMI of 25-29.9 kg/m2, and obesity is typically defined as a BMI of 30 kg/m2 or higher. See, e.g., National Heart, Lung, and Blood Institute, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, The Evidence Report, Washington, D.C.: U.S. Department of Health and Human Services, NIH publication no. 98-4083 (1998).
Recent studies have found that obesity and its associated health risks are not limited to adults, but also affect children and adolescents to a startling degree. According to the Center for Disease Control, the percentage of children and adolescents who are defined as overweight has more than doubled since the early 1970s, and about 15 percent of children and adolescents are now overweight. Risk factors for heart disease, such as high cholesterol and high blood pressure, occur with increased frequency in overweight children and adolescents compared with normal-weight subjects of similar age. Also, type 2 diabetes, previously considered an adult disease, has increased dramatically in children and adolescents. Overweight conditions and obesity are closely linked to type 2 diabetes. It has recently been estimated that overweight adolescents have a 70% chance of becoming overweight or obese adults. The probability increases to about 80% if at least one parent is overweight or obese. The most immediate consequence of being overweight as perceived by children themselves is social discrimination.
Overweight or obese individuals are at increased risk for ailments such as hypertension, dyslipidemia, type 2 (non-insulin dependent) diabetes, insulin resistance, glucose intolerance, hyperinsulinemia, coronary heart disease, angine pectoris, congestive heart failure, stroke, gallstones, cholescystitis, cholelithiasis, gout, osteoarthritis, obstructive sleep apnea and respiratory problems, gall bladder disease, certain forms of cancer (e.g., endometrial, breast, prostate, and colon) and psychological disorders (such as depression, eating disorders, distorted body image and low self esteem). The negative health consequences of obesity make it the second leading cause of preventable death in the United States and impart a significant economic and psychosocial effect on society. See, e.g., McGinnis et al, JAMA (1993) 270:2207-2212.
Obesity is now recognized as a chronic disease that requires treatment to reduce its associated health risks. Although weight loss is an important treatment outcome, one of the main goals of obesity management is to improve cardiovascular and metabolic values to reduce obesity-related morbidity and mortality. It has been shown that 5-10% loss of body weight can substantially improve metabolic values, such as blood glucose, blood pressure, and lipid concentrations. Hence, it is believed that a 5-10% reduction in body weight may reduce morbidity and mortality.
Currently available prescription drugs for managing obesity generally reduce weight by decreasing dietary fat absorption, as with orlistat, or by creating an energy deficit be reducing food intake and/or increasing energy expenditure, as seen with sibutramine. The search for alternatives to presently available antiobesity agents has taken several paths one of which has focused on certain gut peptides that have been implicated in modulating satiety such as peptide YY (PYY) (Chaudhri et al, Annu Rev Physiol (2008) 70:239-255).
C. Atherosclerosis
Atherosclerosis is a complex disease characterized by inflammation, lipid accumulation, cell death and fibrosis. Atherosclerosis is characterized by cholesterol deposition and monocyte infiltration into the subendothelial space, resulting in foam cell formation. Thrombosis subsequent to atherosclerosis leads to myocardial infarction and stroke. Atherosclerosis is the leading cause of mortality in many countries, including the United States. (See, e.g., Ruggeri, Nat Med (2002) 8:1227-1234; Arehart et al, Circ Res, 2008, March 6 Epub ahead of print.)
D. Inflammatory Bowel Disease (IBD)
Inflammatory bowel disease (IBD) is the general name for diseases that cause inflammation in the intestines and includes, e.g. Crohn's disease, ulcerative colitis, ulcerative proctitis. U.S. medical costs of inflammatory bowel disease for 1990 have been estimated to be $1.4 to $1.8 billion. Lost productivity has been estimated to have added an additional $0.4 to $0.8 billion, making the estimated cost of inflammatory bowel disease $1.8 to $2.6 billion. (See, e.g., Pearson, Nursing Times (2004) 100:86-90; Hay et al, J Clin Gastroenterol (1992) 14:309-317; Keighley et al, Ailment Pharmacol Ther (2003) 18:66-70.)
Enteritis refers to inflammation of the intestine, especially the small intestine, a general condition that can have any of numerous different causes. Enterocolitis refers to inflammation of the small intestine and colon.
Crohn's disease (CD) is an inflammatory process that can affect any portion of the digestive tract, but is most commonly seen in the last part of the small intestine otherwise called the (terminal) ileum and cecum. Altogether this area is also known as the ileocecal region. Other cases may affect one or more of: the colon only, the small bowel only (duodenum, jejunum and/or ileum), the anus, stomach or esophagus. In contrast with ulcerative colitis, CD usually does not affect the rectum, but frequently affects the anus instead. The inflammation extends deep into the lining of the affected organ. The inflammation can cause pain and can make the intestines empty frequently, resulting in diarrhea. Crohn's disease may also be called enteritis. Granulomatous colitis is another name for Crohn's disease that affects the colon. Ileitis is CD of the ileum which is the third part of the small intestine. Crohn's colitis is CD affecting part or all of the colon.
Ulcerative colitis (UC) is an inflammatory disease of the large intestine, commonly called the colon. UC causes inflammation and ulceration of the inner lining of the colon and rectum. The inflammation of UC is usually most severe in the rectal area with severity diminishing (at a rate that varies from patient to patient) toward the cecum, where the large and small intestine join. Inflammation of the rectum is called proctitis. Inflammation of the sigmoid colon (located just above the rectum) is called sigmoiditis Inflammation involving the entire colon is termed pancolitis. The inflammation causes the colon to empty frequently resulting in diarrhea. As the lining of the colon is destroyed ulcers form releasing mucus, pus and blood. Ulcerative proctitis is a form of UC that affects only the rectum.
E. Peptide YY (PYY)
Peptide YY (PYY) is a 36 amino acid peptide originally isolated in 1980 from porcine intestine (Tatemoto et al, Nature (1980) 285:417-418). PYY is secreted from enteroendocrine L-cells within both the large and small intestine. It has been shown that in rat and human gut concentrations of immunoreactive PYY are low in duodenum and jenunum, high in ileum and colon, and highest in rectum (Lundberg et al, PNAS USA (1982) 79:4471-4475; Adrian et al, Gastroenterol (1985) 89:1070-1077; Ekblad et al, Peptides (2002) 23:251-261; Ueno et al, Regul Pept (2008) 145:12-16). (PYY expression in rat been reported to also extend to alpha cells of the islets of Langerhans and to cells in the medulla oblongata (Ekblad et al, Peptides (2002) 23:251-261; PYY is released into the circulation as PYY1-36 and PYY3-36 (Eberlein et al, Peptides (1989) 10:797-803). PYY3-36 is generated from PYY1-36 by cleavage of the N-terminal Tyr and Pro residues by dipeptidyl peptidase IV. PYY3-36 is the predominant form of PYY in human postprandial plasma (Grandt et al, Regul Pept (1994) 51:151-159). PYY1-36 and PYY3-36 have been reported to have comparable agonist activity at NPY Y2 receptor (Y2R), a G protein-coupled receptor (Parker et al, Br J Pharmacol (2008) 153:420-431); however, PYY3-36 has been reported to be a high-affinity Y2R selective agonist (Keire et al, Am J Physiol Gastrointest Liver Physiol (2000) 279:G126-G131). PYY was subsequently reported to reduce high-fat food intake in rats after peripheral administration (Okada et al, Endocrinology Supplement (1993) 180) and to cause weight loss in mice after peripheral administration (Morley et al, Life Sciences (1987) 41:2157-2165).
Peripheral administration of PYY3-36 has been reported to markedly reduce food intake and weight gain in rats, to decrease appetite and food intake in humans, and to decrease food intake in mice, but not in Y2R-null mice, which was said to suggest that the food intake effect requires the Y2R. In human studies, infusion of PYY3-36 was found to significantly decrease appetite and reduce food intake by 33% over 24 hours. Infusion of PYY3-36 to reach the normal postprandial circulatory concentrations of the peptide led to peak serum levels of PYY3-36 within 15 minutes, followed by a rapid decline to basal levels within 30 minutes. It was reported that there was significant inhibition of food intake in the 12-hour period following the PYY3-36 infusion, but was essentially no effect on food intake in the 12-hour to 24-hour period. In a rat study, repeated administration of PYY3-36 intraperitoneally (injections twice daily for 7 days) reduced cumulative food intake (Batterham et al, Nature (2002) 418:650-654; Renshaw et al, Current Drug Targets (2005) 6:171-179).
Peripheral administration of PYY3-36 has been reported to reduce food intake, body weight gain and glycemic indices in diverse rodent models of metabolic diseases of both sexes (Pittner et al, Int J Obes Relat Metab Disord (2004) 28:963-971). It has been reported that blockade of Y2R with the specific antagonist BIIE-246 attenuates the effect of peripherally administered endogenous and exogenous PYY3-36 for reducing food intake (Abbott et al, Brain Res (2005) 1043:139-144). It has been reported that peripheral administration of a novel long-acting selective Y2R polyethylene glycol-conjugated peptide agonist reduces food intake and improves glucose metabolism (glucose disposal, plasma insulin and plasma glucose) in rodents (Ortiz et al, JPET (2007) 323:692-700; Lamb et al, J Med Chem (2007) 50:2264-2268). It has been reported that PYY ablation in mice leads to the development of hyperinsulinemia and obesity (Boey et al, Diabetologia (2006) 49:1360-1370). It has been reported that peripheral administration of a long-acting, potent and highly selective Y2R agonist inhibits food intake and promotes fat metabolism in mice (Balasubramaniam et al, Peptides (2007) 28:235-240).
There is evidence that agents which stimulate PYY synthesis in vivo can confer protection against diet-induced and genetic obesity and can improve glucose tolerance (Boey et al, Neuropeptides (2008) 42:19-30).
It has been reported that Y2R agonists such as PYY1-36 and PYY3-36 can confer protection against epileptic seizures, such as against kainate seizures (El Bahh et al, Eur J Neurosci (2005) 22:1417-1430; Woldbye et al, Neurobiology of Disease (2005) 20:760-772).
It has been reported that Y2R agonists such as PYY1-36 and PYY3-36 act as proabsorbtive (or anti-secretory) hormones, increasing upon intravenous administration the absorption of both water and sodium in various parts of the bowel (Bilchik et al, Gastroenterol (1993) 105:1441-1448; Liu et al, J Surg Res (1995) 58:6-11; Nightingale et al, Gut (1996) 39:267-272; Liu et al, Am Surg (1996) 62:232-236; Balasubramaniam et al, J Med Chem (2000) 43:3420-3427). It has been reported that Y2R agonists such as PYY analogues inhibit secretion and promote absorption and growth in the intestinal epithelium (Balasubramaniam et al, J Med Chem (2000) 43:3420-3427). It has been reported that PYY promotes intestinal growth in normal rats (Gomez et al, Am J Physiol (1995) 268:G71-G81). It has been reported that Y2R agonists such as PYY1-36 and PYY3-36 inhibit bowel motility and work to prevent diarrhea (EP1902730; also see Cox, Peptides (2007) 28:345-351).
It has been reported that Y2R agonists such as PYY1-36 and PYY3-36 can confer protection against inflammatory bowel disease such as ulcerative colitis and Crohn's disease (WO 03/105763). It has been reported that PYY-deficient mice exhibit an osteopenic phenotype, i.e. that PYY can increase bone mass and/or can confer protection against loss of bone mass (e.g., decreases loss of bone mass) (Wortley et al, Gastroenterol (2007) 133:1534-1543). It has been reported that PYY3-36 can confer protection in rodent models of pancreatitis (Vona-Davis et al, Peptides (2007) 28:334-338).
It has been reported that angiogenesis is impaired in Y2R-deficient mice (Lee et al, Peptides (2003) 24:99-106), i.e. that agonists of Y2R such as PYY1-36 and PYY3-36 promote angiogenesis. It has been reported that would healing is impaired in Y2R-deficient mice (Ekstrand et al, PNAS USA (2003) 100:6033-6038), i.e. that agonists of Y2R such as PYY1-36 and PYY3-36 promote wound healing. It has been reported that ischemic angiogenesis is impaired in Y2R-deficient mice (Lee et al, J Clin Invest (2003) 111:1853-1862), i.e. that agonists of Y2R such as PYY1-36 and PYY3-36 promotes revascularization and restoration of function of ischemic tissue. It has been reported that agonists of Y2R such as PYY1-36 and PYY3-36 mediate increases in collateral-dependent blood flow in a rat model of peripheral arterial disease (Cruze et al, Peptides (2007) 28:269-280).
It has been reported that PYY and Y2R agonists such as PYY3-36 can suppress tumor growth in the cases of, e.g., pancreatic cancer such as pancreatic ductal adenocarcinoma, breast cancer such as breast infiltrative ductal adenocarcinoma, colon cancer such as colon adenocarcinoma and Barrett's adenocarcinoma (Liu et al, Surgery (1995) 118:229-236; Liu et al, J Surg Res (1995) 58:707-712; Grise et al, J Surg Res (1999) 82:151-155; Tseng et al, Peptides (2002) 23:389-395; McFadden et al, Am J Surg (2004) 188:516-519).
It has been reported that stimulation of Y2R such as by PYY3-36 leads to an increase in plasma adiponectin (Ortiz et al, JPET (2007) 323:692-700). Adiponectin is an adipokine with potent anti-inflammatory properties (Ouchi et al, Clin Chim Acta (2007) 380:24-30; Tilg et al, Nat Rev Immunol (2006) 6:772-783). Adiponectin exerts anti-atherogenic effects by targeting vascular endothelial cells and macrophages and insulin-sensitizing effects, predominantly in muscle and liver (Kubota et al, J Biol Chem (2002) 277:25863-25866; Maeda et al, Nat Med (2002) 8:731-737). Low adiponectin levels have been reported to be associated with atherogenic lipoproteins in dyslipidemia (elevated triglycerides, small dense LDL cholesterol, low HDL cholesterol) (Marso et al, Diabetes Care (2008) February 5 Epub ahead of print). Adiponectin has been implicated in high density lipoprotein (HDL) assembly (Oku et al, FEBS Letters (2007) 581:5029-5033). Adiponectin has been found to ameliorate the abnormalities of metabolic syndrome, including insulin resistance, hyperglycemia, and dyslipidemia, in a mouse model of obesity-linked metabolic syndrome associated with decreased adiponectin levels (Hara et al, Diabetes Care (2006) 29:1357-1362). Adiponectin has been reported to stimulate angiogenesis in response to tissue ischemia (Shibata et al, J Biol Chem (2004) 279:28670-28674). Adiponectin has been reported to prevent cerebral ischemic injury through endothelial nitric oxide synthase-dependent mechanisms (Nishimura et al, Circulation (2008) 117:216-223). Adiponectin has been reported to confer protection against myocardial ischemia-reperfusion injury (Shibata et al, Nat Med (2005) 11:1096-1103; Tao et al, Circulation (2007) 115:1408-1416). Adiponectin has been reported to confer protection against myocardial ischaemia-reperfusion injury via AMP-activated protein kinase, Akt, and nitric oxide (Gonon et al, Cardiovasc Res (2008) 78:116-122). Adiponectin has been reported to confer protection against the development of systolic dysfunction following myocardial infarction, through its abilities to suppress cardiac hypertrophy and interstitial fibrosis, and protect against myocyte and capillary loss (Shibata et al, J Mol Cell Cardiol (2007) 42:1065-1074). Adiponectin has been reported to confer protection against inflammatory lung disease; adiponectin-deficient mice exhibit an emphysema-like phenotype (Summer et al, Am J Physiol Lung Cell Mol Physiol (Mar. 7, 2008)). Adiponectin has been reported to confer protection against allergic airway inflammation and airway hyperresponsiveness such as may be associated with asthma (Shore et al, J Allergy Clin Immunol (2006) 118:389-395). Adiponectin has been suggested to confer protection against pulmonary arterial hypertension by virtue of its insulin-sensitizing effects (Hansmann et al, Circulation (2007) 115:1275-1284). Adiponectin has been reported to ameliorate obesity-related hypertension, with said amelioration of hypertension being associated in part with upregulated prostacyclin expression (Ohashi et al, Hypertension (2006) 47:1108-1116). Adiponectin has been reported to decrease tumor necrosis factor (TNF)-α-induced expression of the adhesion molecules VCAM-1, E-selectin and ICAM-1 in human aortic endothelial cells (HAECs) (Ouchi et al, Circulation (1999) 100:2473-2476) and to inhibit production of TNF-α in macrophages (Yokota et al, Blood (2000) 96:1723-1732). Adiponectin has been reported to confer protection against restenosis after vascular intervention (Matsuda et al, J Biol Chem (2002) 277:37487-37491). The central role of TNF-α in inflammation has been demonstrated by the ability of agents that block the action of TNF-α to treat a range of inflammatory conditions. TNF-α-mediated inflammatory conditions encompass rheumatoid arthritis, inflammatory bowel disease such as Crohn's disease, ankylosing spondylitis, psoriasis, ischemic brain injury, cardiac allograft rejection, asthma, and the like (Bradley, J Pathol (2008) 214:149-160). See, e.g., Yamamoto et al, Clinical Science (2002) 103:137-142; Behre, Scand J Clin Lab Invest (2007) 67:449-458; Guerre-Millo, Diabetes & Metabolism (2008) 34:12-18; Parker et al, Br J Pharmacol (2008) 153:420-431.
F. Treatment of Conditions Modulated by PYY
An attractive alternative approach for treatment of conditions modulated by PYY is to develop an orally active composition for increasing an endogenous level of PYY in an individual, such as an endogenous level of plasma PYY, such as by stimulation of PYY secretion in gut enteroendocrine cells.
G. GPR119
GPR119 is a G protein-coupled receptor (GPR119; e.g., human GPR119, GenBank® Accession No. AAP72125 and alleles thereof; e.g., mouse GPR119, GenBank® Accession No. AY288423 and alleles thereof). GPR119 stimulation as by an agonist leads to elevation of the level of intracellular cAMP, consistent with GPR119 being coupled to Gs. In the patent literature, GPR119 has been referred to as RUP3 (e.g., WO 00/31258); GPR119 has also been referred to as Glucose-Dependent Insulinotropic Receptor (GDIR).
H. G Protein-Coupled Receptors
Although a number of receptor classes exist in humans, by far the most abundant and therapeutically relevant is represented by the G protein-coupled receptor (GPCR) class. It is estimated that there are some 30,000-40,000 genes within the human genome, and of these, approximately 2% are estimated to code for GPCRs.
GPCRs represent an important area for the development of pharmaceutical products. Drugs active at GPCRs have therapeutic benefit across a broad spectrum of human diseases as diverse as pain, cognitive dysfunction, hypertension, peptic ulcers, rhinitis, and asthma. Of the approximately 500 clinically marketed drugs, greater than 30% are modulators of GPCR function. These drugs exert their activity at approximately 30 well-characterized GPCRs. (See, e.g., Wise et al, Annu Rev Pharmacol Toxicol (2004) 44:43-66.)
GPCRs share a common structural motif, having seven sequences of between 22 to 24 hydrophobic amino acids that form seven alpha helices, each of which spans the membrane (each span is identified by number, i.e., transmembrane-1 (TM-1), transmembrane-2 (TM-2), etc.). The transmembrane helices are joined by strands of amino acids between transmembrane-2 and transmembrane-3, transmembrane-4 and transmembrane-5, and transmembrane-6 and transmembrane-7 on the exterior, or “extracellular” side, of the cell membrane (these are referred to as “extracellular” regions 1, 2 and 3 (EC-1, EC-2 and EC-3), respectively). The transmembrane helices are also joined by strands of amino acids between transmembrane-1 and transmembrane-2, transmembrane-3 and transmembrane-4, and transmembrane-5 and transmembrane-6 on the interior, or “intracellular” side, of the cell membrane (these are referred to as “intracellular” regions 1, 2 and 3 (IC-1, IC-2 and IC-3), respectively). The “carboxy” (“C”) terminus of the receptor lies in the intracellular space within the cell, and the “amino” (“N”) terminus of the receptor lies in the extracellular space outside of the cell.
Generally, when a ligand binds with the receptor (often referred to as “activation” of the receptor), there is a change in the conformation of the receptor that facilitates coupling between the intracellular region and an intracellular “G-protein.” It has been reported that GPCRs are “promiscuous” with respect to G proteins, i.e., that a GPCR can interact with more than one G protein. See, Kenakin, Life Sciences (1988) 43:1095-1101. Although other G proteins exist, currently, Gq, Gs, Gi, Gz and Go are G proteins that have been identified. Ligand-activated GPCR coupling with the G-protein initiates a signaling cascade process (referred to as “signal transduction”). Under normal conditions, signal transduction ultimately results in cellular activation or cellular inhibition. Although not wishing to be bound to theory, it is thought that the IC-3 loop as well as the carboxy terminus of the receptor interact with the G protein.
There are also promiscuous G proteins, which appear to couple several classes of GPCRs to the phospholipase C pathway, such as G15 or G16 (Offermanns & Simon, J Biol Chem (1995) 270:15175-80), or chimeric G proteins designed to couple a large number of different GPCRs to the same pathway, e.g. phospholipase C (Milligan & Rees, Trends in Pharmaceutical Sciences (1999) 20:118-24).
Under physiological conditions, GPCRs exist in the cell membrane in equilibrium between two different conformations: an “inactive” state and an “active” state. A receptor in an inactive state is unable to link to the intracellular signaling transduction pathway to initiate signal transduction leading to a biological response. Changing the receptor conformation to the active state allows linkage to the transduction pathway (via the G-protein) and produces a biological response.
A receptor may be stabilized in an active state by a ligand or a compound such as a drug. Recent discoveries, including but not exclusively limited to modifications to the amino acid sequence of the receptor, provide means other than ligands or drugs to promote and stabilize the receptor in the active state conformation. These means effectively stabilize the receptor in an active state by simulating the effect of a ligand binding to the receptor. Stabilization by such ligand-independent means is termed “constitutive receptor activation.”